SAGD (Steam Assisted Gravity Drainage) is a proven effective commercial process to recover heavy oil and oil sands and has been widely used in Canadian Oil sands recovery. As shown in FIGS. 1 and 2, the SAGD process creates a steam chamber 10 under the ground G in a hydrocarbon formation B around a generally horizontal steam injection pipe 12 where steam is injected into the steam chamber 10 and heats and reduces the viscosity of oil in the area to produce the oil from a production pipe 14 that is arranged below the steam injection pipe 12. The process is operated over an extended period of time while the steam chamber 10 continuously expands. Predicting the velocity of the expanding SAGD stream chamber 10 or more specifically, the velocity of the front 20 of the SAGD steam chamber plays a critical role in the interpretation and prediction of performance of SAGD process and the management and operation of a SAGD production system. The faster the front 20 moves and the bigger the steam chamber 10 expands results in a higher oil production rate and the larger the total recovery of oil from the SAGD system.
At present, four dimensional (4D) seismic interpretation data can only dynamically map surfaces that have a temperature of 60 degrees C. which is much lower than the steam saturation temperature. So the portion of the formation mapped by the 4D seismic technique is actually quite a bit larger than the steam chamber 10 and thus, 4D seismic data will overestimate the size of steam chamber 10. Also, if the front 20 is moving or progressing slowly, the size overestimation of the steam chamber 10 is likely to be higher or magnified.
Reservoir simulation has the capability of simulating steam chamber geometry, but with an insurmountable drawback of extremely slow speed in field study with multiple pairs of SAGD wells.
It is desirable to create an analytical tool that is fast and can be easily calibrated with field observation well data to make good predictions of the location and velocity of the steam front in a SAGD production system.